This application claims the benefit of priority under 35 U.S.C. xc2xa7 119 from Norwegian Application No. 20005115, filed Oct. 11, 2000.
The present invention relates to a device for cooling a light source in a compact projector.
The current tendency is that the market in general desires small, compact and lightweight products. This trend also applies to video projectors. However, along with such a miniaturization of, for example, a video projector, there is also a need to minimize noise.
Theoretically it should be possible for a video projector to be noiseless, as it should be able to consist of only optical and electronic components. However, one of the main components of projectors is a strong light source, e.g., 120 watts or more, which generates substantial amounts of heat. The heat generated by the light source would damage the entire projector in the absence of a device for removing this heat. Thus, it is necessary to provide for the cooling or, alternatively, the removal of the heat with the aid, for example, of fans. However, fans used in devices of this type generate audible noise. Miniaturization of the components, including the fan, would not eliminate the noise because a smaller fan must be driven at a higher speed to produce an air flow that is sufficiently powerful to cool the projector and prevent heat damage.
With today""s large video projectors this is not a serious problem because large, robust fans can be used to effectively remove the heat at low rotational speeds (RPM). The difficulties arise in compact projectors that use smaller fans, which are not constructed to withstand high temperatures. When a smaller, high flow-rate fan is used for removal of heat by suction of the hot air away from the light source and other overheated components, the fan itself will become heated and lubrication in its bearings will dry out faster, thereby reducing the service life of the fan.
In accordance with the present invention, a device for cooling a projector includes a plurality of air intakes positioned upstream from a suction fan having an integrated motor. A light source of the projector is disposed between a first one of the air intakes and the suction fan. The first air intake admits a first flow of air, drawn by the fan, that flows around and pulls heat away from the light source. A second one of the air intakes is arranged to admit a second flow of air, also drawn by the fan. The second flow of air passes through a duct that includes an outlet opening positioned adjacent an upstream side of the suction fan. The duct has a longitudinal axis that, at the outlet opening, is substantially coincident with the rotational axis of the fan motor so that the duct directs the second flow of air against the fan motor. The second flow of air, which has a temperature that is not substantially affected by the light source, cools the fan motor and forms an insulating layer that protects the fan motor from being damaged by the high temperatures of the first air flow.
An optional louver is positioned between the light source and the fan to prevent light from being emitted through the fan and to help direct the first flow of air evenly across the fan.
Additional aspects and advantages of this invention will be apparent from the following detailed description of a preferred embodiment thereof, which proceeds with reference to the accompanying drawings.